The present invention pertains to blends (A) of interpolymers made from monomer components comprising at least one xcex1-olefin and at least one aromatic vinylidene monomer and/or at least one hindered aliphatic vinylidene monomer and/or at least one cycloaliphatic vinylidene monomer and (B) olefinic polymers.
The generic class of materials covered by xcex1-olefin/hindered vinylidene monomer substantially random interpolymers and including materials such as xcex1-olefin/vinyl aromatic monomer interpolymers are known in the art and offer a range of material structures and properties which makes them useful for varied applications, such as compatibilizers for blends of polyethylene and polystyrene as described in U.S. Pat. No. 5,460,818.
One particular aspect described by D""Anniello et al. (Journal is of Applied Polymer Science, Volume 58, pages 1701-1706 (1995)) is that such interpolymers can show good elastic properties and energy a dissipation characteristics. In another aspect, selected interpolymers can find utility in adhesive systems, as illustrated in U.S. Pat. No. 5,244,996, issued to Mitsui Petrochemical Industries Ltd.
Although of utility in their own right, Industry is constantly seeking to improve the applicability of these interpolymers, for example to extend the temperature range of application. Such enhancements may be accomplished via additives, but it is desirable to develop technologies to provide improvements in processability or performance without the addition of additives or further improvements than can be achieved with the addition of additives.
Park et al., in WO 95/27755 describes a method of increasing the toughness and solvent resistance of a homopolymer or interpolymer of a monovinylidene aromatic monomer, by blending it with an olefin polymer such as a polyethylene or ethylene/octene copolymer. However because of the incompatability of these two types of resins, there is a requirement for a compatabilizer which Park teaches can be a pseudo random interpolymer of an aliphatic xcex1-olefin and a vinylidene aromatic monomer.
Bradfute et al., in WO 95/32095 discloses multilayer films having at least one layer which is an ethylene/styrene copolymer.
McKay et al., in WO 96/07681 describes a thermoset elastomer comprising a crosslinked pseudorandom or substantially random interpolymer of at least one xcex1-olefin, at least one vinylidene aromatic compound, and at least one diene. The subject invention also provides a thermoplastic vulcanizate comprising the thermoset elastomer as provided in a themoplastic polyolefin matrix.
There is a need to provide materials based on xcex1-olefin/vinylidene aromatic monomer interpolymers with superior performance characteristics to the unmodified polymers, which will further expand the utility of this interesting class of materials. This superior characteristics include, but are not limited to, low temperature toughness, mechanical strength and melt processability.
The present invention pertains to a fabricated article other than a film comprising a blend of polymeric materials consisting of
(A) from 1 to 99 weight percent of one or more (xcex1-olefin/vinylidene monomer non-crosslinked substantially random interpolymers, wherein the distribution of the monomers of said interpolymers can be described by the Bernoulli statistical model or by a first or second order Markovian statistical model, and each having been made from monomer components comprising:
(1) from 0.5 to 65 mole percent of either
(a) at least one vinylidene aromatic monomer, or
(b) at least one hindered aliphatic vinylidene monomer, corresponding to the formula: 
wherein A1 is a sterically bulky, aliphatic or cycloaliphatic substituent of up to 20 carbons, R1 is selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl; each R2 is independently selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl; or alternatively R1 and A1 together form a ring system or
(c) a combination of at least one vinylidene aromatic monomer and at least one hindered aliphatic vinylidene monomer; and
(2) from 35 to 99.5 mole percent of at least one aliphatic xcex1-olefin having from 2 to 20 carbon atoms; and
(B) from 99 to 1 weight percent of one or more homopolymers or copolymers of monomer components comprising aliphatic xcex1-olefins having from 2 to 20 carbon atoms, or aliphatic xcex1-olefins having from 2 to 20 carbon atoms and containing polar groups.
The present invention also pertains to an expandable composition comprising the aforementioned blend and a foaming or expansion agent.
The blends and or foams of the present invention can xe2x80x9ccomprisexe2x80x9d, xe2x80x9cconsist essentially ofxe2x80x9d or xe2x80x9cconsist ofxe2x80x9d any two or more of such polymers or interpolymers enumerated herein.
These blends provide an improvement in one or more of the polymer properties such as, but not limited to, mechanical properties, low temperature performance, relaxation/damping behavior and melt flow properties as compared to a like property of either of the individual polymers of said blend.
The term xe2x80x9cinterpolymerxe2x80x9d is used herein to indicate a polymer wherein at least two different monomers are polymerized to make the interpolymer.
The term xe2x80x9ccopolymerxe2x80x9d as employed herein means a polymer wherein at least two different monomers are polymerized to form the copolymer.
The term xe2x80x9cmer(s)xe2x80x9d means the polymerized unit of the polymer derived from the indicated monomer(s).
The term xe2x80x9cmonomer residuexe2x80x9d or xe2x80x9cpolymer units derived fromxe2x80x9d means that portion of the polymerizable monomer molecule which resides in the polymer chain as a result of being polymerized with another polymerizable molecule to make the polymer chain.
The term xe2x80x9csubstantially randomxe2x80x9d in the substantially random interpolymer resulting from polymerizing one or more xcex1-olefin monomers and one or more vinylidene aromatic monomers or hindered aliphatic or cycloaliphatic vinylidene monomers, and optionally, with other polymerizable ethylenically unsaturated monomer(s) as used herein means that the distribution of the monomers of said interpolymer can be described by the Bernoulli statistical model or by a first or second order Markovian statistical model, as described by J. C. Randall in POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method, Academic Press New York, 1977, pp. 71-78. Preferably, the substantially random interpolymer resulting from polymerizing one or more xcex1-olefin monomers and one or more vinylidene aromatic monomer, and optionally, with other polymerizable ethylenically unsaturated monomer(s) does not contain more than 15 percent of the total amount of vinylidene aromatic monomer in blocks of vinylidene aromatic monomer of more than 3 units. More preferably, the interpolymer was not characterized by a high degree of either isotacticity or syndiotacticity. This means that in the carbonxe2x88x9213 NMR spectrum of the substantially random interpolymer the peak areas corresponding to the main chain methylene and methine carbons representing either meso diad sequences or racemic diad sequences should not exceed 75 percent of the total peak area of the main chain methylene and methine carbons.
Any numerical values recited herein include all values from the lower value to the upper value in increments of one unit provided that there is a separation of at least 2 units between any lower value and any higher value. As an example, if it is stated that the amount of a component or a value of a process variable such as, for example, temperature, pressure, time is, for example, from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are expressly enumerated in this specification. For values which are less than one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.
The interpolymers suitable as component (A) for the blends comprising the present invention include substantially random interpolymers each having been made from monomer components comprising one or more xcex1-olefin monomers with one or more vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinylidene monomers, and optionally with other polymerizable ethylenically unsaturated monomer(s). The interpolymers are also prepared by polymerizing one or more xcex1-olefin monomers with one or more vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinylidene monomers, and optionally with other polymerizable ethylenically unsaturated monomer(s).
Suitable xcex1-olefin monomers include for example, xcex1-olefin monomers containing from 2 to 20, preferably from 2 to 12, more preferably from 2 to 8 carbon atoms. Preferred such monomers include ethylene, propylene, butene-1,4-methyl-1-pentene, hexene-1 and octene-1. Most preferred are ethylene or a combination of ethylene with C3-8 xcex1-olefins. These xcex1-olefins do not contain an aromatic moiety.
Other optional polymerizable ethylenically unsaturated monomer(s) include strained ring olefins such as norbornene and C1-10 alkyl or C6-10 aryl substituted norbornenes, with an exemplary interpolymer being ethylene/styrene/norbornene.
Suitable vinylidene aromatic monomers which can be employed to prepare the interpolymers employed in the blends include, for example, those represented by the following formula: 
wherein R1 is selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl; each R2 is independently selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl; Ar is a phenyl group or a phenyl group substituted- with from 1 to 5 substituents selected from the group consisting of halo, C1-4-alkyl, and C1-4-haloalkyl; and n has a value from zero to 4, preferably from zero to 2, most preferably zero. Exemplary monovinylidene aromatic monomers include styrene, vinyl toluene, xcex1-methylstyrene, t-butyl styrene, chlorostyrene, including all isomers of these compounds. Particularly suitable such monomers include styrene and lower alkyl- or halogen-substituted derivatives thereof. Preferred monomers include styrene, xcex1-methyl styrene, the lower alkyl-(C1-C4) or phenyl-ring substituted derivatives of styrene, such as for example, ortho-, meta-, and para-methylstyrene, the ring halogenated styrenes, para-vinyl toluene or mixtures thereof. A more preferred aromatic monovinylidene monomer is styrene.
By the term xe2x80x9chindered aliphatic or cycloaliphatic vinylidene compoundsxe2x80x9d, it is meant addition polymerizable vinylidene monomers corresponding to the formula: 
wherein A1 is a sterically bulky, aliphatic or cycloaliphatic substituent of up to 20 carbons, R1 is selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl; each R2 is independently selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl; or alternatively R1 and A1 together form a ring system. By the term xe2x80x9csterically bulkyxe2x80x9d is meant that the monomer bearing this substituent is normally incapable of addition polymerization by standard Ziegler-Natta polymerization catalysts at a rate comparable with ethylene polymerizations. xcex1-Olefin monomers containing from 2 to 20 carbon atoms and having a linear aliphatic structure such as propylene, butene-1, hexene-1 and octene-1 are not considered as hindered aliphatic monomers. Preferred hindered aliphatic or cycloaliphatic vinylidene compounds are monomers in which one of the carbon atoms bearing ethylenic unsaturation is tertiary or quaternary substituted. Examples of such substituents include cyclic aliphatic groups such as cyclohexyl, cyclohexenyl, cyclooctenyl, or ring alkyl or aryl substituted derivatives thereof, tert-butyl, and norbornyl. Most preferred hindered aliphatic or cycloaliphatic vinylidene compounds are the various isomeric vinyl-ring substituted derivatives of cyclohexene and substituted cyclohexenes, and 5-ethylidene-2-norbornene. Especially suitable are 1-, 3-, and 4-vinylcyclohexene.
The interpolymers of one or more xcex1-olefins and one or more monovinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinylidene monomers employed in the present invention are substantially random polymers. These interpolymers usually contain from 0.5 to 65, preferably from 1 to 55, more preferably from 2 to 50 mole percent of at least one vinylidene aromatic monomer and/or hindered aliphatic or cycloaliphatic vinylidene monomer and from 35 to 99.5, preferably from 45 to 99, more preferably from 50 to 98 mole percent of at least one aliphatic xcex1-olefin having from 2 to 20 carbon atoms.
Other optional polymerizable ethylenically unsaturated monomer(s) include strained ring olefins such as norbornene and C1-10 alkyl or C6-10 aryl substituted norbornenes, with an exemplary interpolymer being ethylene/styrene/norbornene.
The number average molecular weight (Mn) of the polymers and interpolymers is usually greater than 5,000, preferably from 20,000 to 1,000,000, more preferably from 50,000 to 500,000.
Polymerizations and unreacted monomer removal at temperatures above the autopolymerization temperature of the respective monomers may result in formation of some amounts of homopolymer polymerization products resulting from free radical polymerization. For example, while preparing the substantially random interpolymer, an amount of atactic vinylidene aromatic homopolymer may be formed due to homopolymerization of the vinylidene aromatic monomer at elevated temperatures. The presence of vinylidene aromatic homopolymer is in general not detrimental for the purposes of the present invention and can be tolerated. The vinylidene aromatic homopolymer may be separated from the interpolymer, if desired, by extraction techniques such as selective precipitation from solution with a non solvent for either the interpolymer or the vinylidene aromatic homopolymer. For the purpose of the present invention it is preferred that no more than 20 weight percent, preferably less than 15 weight percent based on the total weight of the interpolymers of vinylidene aromatic homopolymer is present.
The substantially random interpolymers may be modified by typical grafting, hydrogenation, functionalizing, or other reactions well known to those skilled in the art. The polymers may be readily is sulfonated or chlorinated to provide functionalized derivatives according to established techniques.
The substantially random interpolymers can be produced by polymerization or copolymerization of the appropriate monomers in t the presence of a metallocene catalyst and a co-catalyst as described in EP-A-0,416,815 by James C. Stevens et al., and U.S. Pat. No. 5,703,187 by Francis J. Timmers. Preferred operating conditions for such polymerization reactions are pressures from atmospheric up to 3,000 atmospheres and temperatures from xe2x88x9230xc2x0 C. to 200xc2x0 C.
Examples of suitable catalysts and methods for preparing the substantially random interpolymers are disclosed in EP-A-514,828; as well as U.S. Pat. Nos. 5,055,438; 5,057,475; 5,096,867; 5,064,802; 5,132,380; 5,189,192; 5,321,106; 5,347,024; 5,350,723; 5,374,696; 5,399,635; 5,470,993; 5,703,187; and 5,721,185.
The substantially random xcex1-olefin/vinylidene aromatic interpolymers can also be prepared by the methods described by John G. Bradfute et al. (W. R. Grace and Co.) in WO 95/32095; by R. B. Pannell (Exxon Chemical Patents, Inc.) in WO 94/00500; and in Plastics Technology, p. 25 (September 1992).
Also suitable are the substantially random interpolymers which comprise at least one xcex1-olefin/vinyl aromatic/vinyl aromatic/xcex1-olefin tetrad disclosed in WO 98/09999 by Francis J. Timmers et al. These interpolymers contain additional signals with intensities greater than three times the peak to peak noise. These signals appear in the chemical shift range 43.70-44.25 ppm and 38.0-38.5 ppm. Specifically, major peaks are observed at 44.1, 43.9 and 38.2 ppm. A proton test NMR experiment indicates that the signals in the chemical shift region 43.70-44.25 ppm are methine carbons and the signals in the region 38.0-38.5 ppm are methylene carbons.
In order to determine the carbonxe2x88x9213 NMR chemical shifts of the interpolymers described, the following procedures and conditions are employed. A five to ten weight percent polymer solution is prepared in a mixture consisting of 50 volume percent 1,1,2, 2-tetrachloroethane-d2 and 50 volume percent 0.10 molar chromium tris(acetylacetonate) in 1,2,4-trichlorobenzene. NMR spectra are acquired at 130xc2x0 C. using an inverse gated decoupling sequence, a 90xc2x0 pulse width and a pulse delay of five seconds or more. The spectra are referenced to the isolated methylene signal of the polymer assigned at 30.000 ppm.
It is believed that these new signals are due to sequences is involving two head-to-tail vinyl aromatic monomer preceded and followed by at least one xcex1-olefin insertion, e.g. an ethylene/styrene/styrene/ethylene tetrad wherein the styrene monomer insertions of said tetrads occur exclusively in a 1,2 (head to tail) manner. It is understood by one skilled in the art that for such tetrads involving a vinyl aromatic monomer other than styrene and an xcex1-olefin other than ethylene that the ethylene/vinyl aromatic monomer/vinyl aromatic monomer/ethylene tetrad will give rise to similar carbonxe2x88x9213 NMR peaks but with slightly different chemical shifts.
These interpolymers are prepared by conducting the polymerization at temperatures of from xe2x88x9230xc2x0 C. to 250xc2x0 C. in the presence of such catalysts as those represented by the formula 
wherein: each Cp is independently, each occurrence, a substituted cyclopentadienyl group xcfx80-bound to M; E is C or Si; M is a group IV metal, preferably Zr or Hf, most preferably Zr; each R is independently, each occurrence, H, hydrocarbyl, silahydrocarbyl, or hydrocarbylsilyl, containing up to 30 preferably from 1 to 20 more preferably from 1 to 10 carbon or silicon atoms; each Rxe2x80x2 is independently, each occurrence, H, halo, hydrocarbyl, hyrocarbyloxy, silahydrocarbyl, hydrocarbylsilyl containing up to 30 preferably from 1 to 20 more preferably from 1 to 10 carbon or silicon atoms or two Rxe2x80x2 groups together can be a C1-10 hydrocarbyl substituted 1,3-butadiene; m is 1 or 2; and optionally, but preferably in the presence of an activating cocatalyst. Particularly, suitable substituted cyclopentadienyl groups include those illustrated by the formula: 
wherein each R is independently, each occurrence, H, hydrocarbyl, silahydrocarbyl, or hydrocarbylsilyl, containing up to 30 preferably from 1 to 20 more preferably from 1 to 10 carbon or silicon atoms or two R groups together form a divalent derivative of such group. Preferably, R independently each occurrence is (including where appropriate all isomers) hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, phenyl or silyl or (where appropriate) two such R groups are linked together forming a fused ring system such as indenyl, fluorenyl, tetrahydroindenyl, tetrahydrofluorenyl, or octahydrofluorenyl.
Particularly preferred catalysts include, for example, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl))zirconium dichloride, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl))zirconium 1,4-diphenyl-1,3-butadiene, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl))zirconium di-C1-4 alkyl, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl))zirconium di-C1-4 alkoxide, or any combination thereof.
Further preparative methods for the interpolymer component (A) of the present invention have been described in the literature. Longo and Grassi (Makromol. Chem., Volume 191, pages 2387 to 2396 [1990]) and D""Anniello et al. (Journal of Applied Polymer Science, Volume 58, pages 1701-1706 [1995]) reported the use of a catalytic system based on methylalumoxane (MAO) and cyclopentadienyltitanium trichloride (CpTiCl3) to prepare an ethylene-styrene copolymer. Xu and Lin (Polymer Preprints, Am. Chem. Soc., Div. Polym. Chem.) Volume 35, pages 686,687 [1994]) have reported copolymerization using a MgCl2/TiCl4/NdCl3/Al(iBu)3 catalyst to give random copolymers of styrene and propylene. Lu et al (Journal of Applied Polymer Science, Volume 53, pages 1453 to 1460 [1994]) have described the copolymerization of ethylene and styrene using a TiCl4/NdCl3/MgCl2Al(Et)3 catalyst. Sernetz and Mulhaupt, (Macromol. Chem. Phys., v. 197, pp 1071-1083, 1997) have described the influence of polymerization conditions on the copolymerization of styrene with ethylene using Me2Si(Me4Cp) (N-tert-butyl)TiCl2/methylaluminoxane Ziegler-Natta catalysts. The manufacture of xcex1-olefin/vinyl aromatic monomer interpolymers such as propylene/styrene and butene/styrene are described in U.S. Pat. No. 5,244,996, issued to Mitsui Petrochemical Industries Ltd.
Olefinic polymers suitable for use as component (B) in the blends according to the present invention are aliphatic xcex1-olefin homopolymers or interpolymers, or interpolymers of one or more aliphatic xcex1-olefins and one or more non-aromatic monomers interpolymerizable therewith such as C2-C20 xcex1-olefins or those aliphatic xcex1-olefins having from 2 to 20 carbon atoms and containing polar groups. Suitable aliphatic xcex1-olefin monomers which introduce polar groups into the polymer include, for example, ethylenically unsaturated nitriles such as acrylonitrile, methacrylonitrile, ethacrylonitrile, etc.; ethylenically unsaturated anhydrides such as maleic anhydride; ethylenically unsaturated amides such as acrylamide, methacrylamide etc.; ethylenically unsaturated carboxylic acids (both mono- and difunctional) such as acrylic acid and methacrylic acid, etc.; esters (especially lower, e.g. C1-C6, alkyl esters) of ethylenically unsaturated carboxylic acids such as methyl methacrylate, ethyl acrylate, hydroxyethylacrylate, n-butyl acrylate or methacrylate, 2-ethyl-hexylacrylate etc.; ethylenically unsaturated dicarboxylic acid imides such as N-alkyl or N-aryl maleimides such as N-phenyl maleimide. Preferably such monomers containing polar groups are acrylic acid, vinyl acetate, maleic anhydride and acrylonitrile. Halogen groups which can be included in the polymers from aliphatic xcex1-olefin monomers include fluorine, chlorine and bromine; preferably such polymers are chlorinated polyethylenes (CPEs). Preferred olefinic polymers for use in the present invention are homopolymers or interpolymers of an aliphatic, including cycloaliphatic, xcex1-olefin having from 2 to 18 carbon atoms. Suitable examples are homopolymers of ethylene or propylene, and interpolymers of two or more xcex1-olefin monomers. Other preferred olefinic polymers are interpolymers of ethylene and one or more other xcex1-olefins having from 3 to 8 carbon atoms. Preferred comonomers include 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. The olefinic polymer blend component (B) may also contain, in addition to the xcex1-olefin, one or more non-aromatic monomers interpolymerizable therewith. Such additional interpolymerizable monomers include, for example, C4-C20 dienes, preferably, butadiene or 5 ethylidene-2-norbornene. The olefinic polymers can be further characterized by their degree of long or short chain branching and the distribution thereof.
One class of olefinic polymers is generally produced by a high pressure polymerization process using a free radical initiator resulting in the traditional long chain branched low density polyethylene (LDPE). LDPE employed in the present composition usually has a density of less than 0.94 g/cc (ASTM D 792) and a melt index of from 0.01 to 100, and preferably from 0.1 to 50 grams per 10 minutes (as determined by ASTM Test Method D 1238, condition I).
Another class is the linear olefin polymers which have an absence of long chain branching, as the traditional linear low density polyethylene polymers (heterogeneous LLDPE) or linear high density polyethylene polymers (HDPE) made using Ziegler polymerization processes (for example, U.S. Pat. No. 4,076,698 (Anderson et al.), sometimes called heterogeneous polymers.
HDPE consists mainly of long linear polyethylene chains. The HDPE employed in the present composition usually has a density of at least 0.94 grams per cubic centimeter (g/cc) as determined by ASTM Test Method D 1505, and a melt index (ASTM-1238, condition I) in the range of from 0.01 to 100, and preferably from 0.1 to 50 grams per 10 minutes.
The heterogeneous LLDPE employed in the present composition generally has a density of from 0.85 to 0.94 g/cc (ASTM D 792), and a melt index (ASTM-1238, condition I) in the range of from 0.01 to 100, and preferably from 0.1 to 50 grams per 10 minutes. Preferably the LLDPE is an interpolymer of ethylene and one or more other xcex1-olefins having from 3 to 18 carbon atoms, more preferably from 3-8 carbon atoms. Preferred comonomers include 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene.
A further class is that of the uniformly branched or homogeneous polymers (homogeneous LLDPE). The homogeneous polymers contain no long chain branches and have only branches derived from the monomers (if having more than two carbon atoms). Homogeneous polymers include those made as described in U.S. Pat. No. 3,645,992 (Elston), and those made using so-called single site catalysts in a batch reactor having relatively high olefin concentrations (as described in U.S. Pat. Nos. 5,026,798 and 5,055,438 (Canich). The uniformly branched/homogeneous polymers are those polymers in which the comonomer is randomly distributed within a given interpolymer molecule and wherein the interpolymer molecules have a similar ethylene/comonomer ratio within that interpolymer.
The homogeneous LLDPE employed in the present composition generally has a density of from 0.85 to 0.94 g/cc (ASTM D 792), and a melt index (ASTM-1238, condition I) in the range of from 0.01 to 100, and preferably from 0.1 to 50 grams per 10 minutes. Preferably the LLDPE is an interpolymer of ethylene and one or more other xcex1-olefins having from 3 to 18 carbon atoms, more preferably from 3-8 carbon atoms. Preferred comonomers include 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene.
Further, there is the class of substantially linear olefin polymers (SLOP) that may advantageously be used in component (B) of the blends of the present invention. These polymers have a processability similar to LDPE, but the strength and toughness of is LLDPE. Similar to the traditional homogeneous polymers, the substantially linear ethylene/xcex1-olefin interpolymers have only a single melting peak, as opposed to traditional Ziegler polymerized heterogeneous linear ethylene/xcex1-olefin interpolymers which have two or more melting peaks (determined using differential scanning calorimetry). Substantially linear olefin polymers are disclosed in U.S. Pat. Nos. 5,272,236 and 5,278,272.
The density of the SLOP as measured in accordance with ASTM D-792 is generally from 0.85 g/cc to 0.97 g/cc, preferably from 0.85 g/cc to 0.955 g/cc, and especially from 0.85 g/cc to 0.92 g/cc.
The melt index, according to ASTM D-1238, Condition 190xc2x0 C./2.16 kg (also known as I2), of the SLOP is generally from 0.01 g/10 min. to 1000 g/10 min., preferably from 0.01 g/10 min. to 100 g/10 min., and especially from 0.01 g/10 min. to 10 g/10 min.
Also, included are the ultra low molecular weight ethylene polymers and ethylene/xcex1-olefin interpolymers described in the provisional patent application (application Ser. No. 60/010,403) entitled Ultra-Low Molecular Weight Polymers, filed provisionally on Jan. 22, 1996, in the names of M. L. Finlayson, C. C. Garrison, R. E. Guerra, M. J. Guest, B. W. S. Kolthammer, D. R. Parikh, and S. M. Ueligger,. These ethylene/xcex1-olefin interpolymers have I2 melt indices greater than 1,000, or a number average molecular weight (Mn) less than 11,000.
The SLOP can be a homopolymer of C2-C20 olefins, such as ethylene, propylene, 4-methyl-1-pentene, etc., or it can be an 40 interpolymer of ethylene with at least one C3-C20 xcex1-olefin and/or C2-C20 acetylenically unsaturated monomer and/or C4-C18 diolefin. SLOP can also be an interpolymer of ethylene with at least one of the above C3-C20 xcex1-olefins, diolefins and/or acetylenically unsaturated monomers in combination with other unsaturated monomers.
Especially preferred olefin polymers suitable for use as component (B) comprise LDPE, HDPE, heterogeneous and homogeneous LLDPE, SLOP, polypropylene (PP), especially isotactic polypropylene and rubber toughened polypropylenes, or-ethylene-propylene interpolymers (EP), or chlorinated polyolefins (CPE), or ethylene-vinyl acetate copolymers, or ethylene-acrylic acid copolymers, or any combination thereof.
The blends of the present invention usually comprise from 1 to 99, preferably from 5 to 95 and more preferably from 10 to 90 percent by weight of the interpolymers containing at least one aromatic vinylidene monomer residue or hindered aliphatic or cycloaliphatic vinylidene monomer residue or any combination thereof (component (A)) and from 1 to 99, preferably from 5 to 95, more preferably from 10 to 90 percent by weight of the polymers which do not contain any aromatic vinylidene monomer residue or hindered aliphatic or cycloaliphatic vinylidene monomer residue (component (B)). The percentages are based on the total amount of the polymers constituting the blends.
The blends of the present invention may be prepared by any suitable means known in the art such as, but not limited to, dry blending in a pelletized form in the desired proportions followed by melt blending in a screw extruder, or Banbury mixer. The dry blended pellets may be directly melt processed into a final solid state article by for example injection molding. Alternatively, the blends may be made by direct polymerization, without isolation of the blend components, using for example one or more catalysts in one reactor or two or more reactors in series or parallel.
The foam structure of the present invention may take any physical configuration known in the art, such as sheet, plank, or bun stock. Other useful forms are expandable or foamable particles, moldable foam particles, or beads, and articles formed by expansion and/or coalescing and welding of those particles.
Excellent teachings to processes for making ethylenic polymer foam structures and processing them are seen in C. P. Park, xe2x80x9cPolyolefin Foamxe2x80x9d, Chapter 9, Handbook of Polymer Foams and Technology, edited by D. Klempner and K. C. Frisch, Hanser Publishers, Munich, Vienna, New York, Barcelona (1991).
The present foam structure may be made by a conventional extrusion foaming process. The structure is generally prepared by heating an ethylenic polymer material to form a plasticized or melt polymer material, incorporating therein a blowing agent to form a foamable gel, and extruding the gel through a die to form the foam product. Prior to mixing with the blowing agent, the polymer material is heated to a temperature at or above its glass transition temperature or melting point. The blowing agent may be incorporated or mixed into the melt polymer material by any means known in the art such as with an extruder, mixer, or blender. The blowing agent is mixed with the melt polymer material at an elevated pressure sufficient to prevent substantial expansion of the melt polymer Is material and to generally disperse the blowing agent homogeneously therein. Optionally, a nucleator may be blended in the polymer melt or dry blended with the polymer material prior to plasticizing or melting. The foamable gel is typically cooled to a lower temperature to optimize physical characteristics of the foam structure. The gel is then extruded or conveyed through a die of desired shape to a zone of reduced or lower pressure to form the foam structure. The zone of lower pressure is at a pressure lower than that in which the foamable gel is maintained prior to extrusion through the die. The lower pressure may be superatmospheric or subatmospheric (vacuum), but is preferably at an atmospheric level.
The present foam structure may be formed in a coalesced strand form by extrusion of the ethylenic polymer material through a multi-orifice die. The orifices are arranged so that contact between adjacent streams of the molten extrudate occurs during the foaming process and the contacting surfaces adhere to one another with sufficient adhesion to result in a unitary foam structure. The streams of molten extrudate exiting the die take the form of strands or profiles, which desirably foam, coalesce, and adhere to one another to form a unitary structure. Desirably, the coalesced individual strands or profiles should remain adhered in a unitary structure to prevent strand delamination under stresses encountered in preparing, shaping, and using the foam. Apparatuses and methods for producing foam structures in coalesced strand form are seen in U.S. Pat. Nos. 3,573,152 and 4,824,720.
The present foam structure may also be formed by an accumulating extrusion process as seen in U.S. Pat. No. 4,323,528. In this process, low density foam structures having large lateral cross-sectional areas are prepared by: 1) forming under pressure a gel of the ethylenic polymer material and a blowing agent at a temperature at which the viscosity of the gel is sufficient to retain the blowing agent when the gel is allowed to expand; 2) extruding the gel into a holding zone maintained at a temperature and pressure which does not allow the gel to foam, the holding zone having an outlet die defining an orifice opening into a zone of lower pressure at which the gel foams, and an openable gate closing the die orifice; 3) periodically opening the gate; 4) substantially concurrently applying mechanical pressure by a movable ram on the gel to eject it from the holding zone through the die orifice into the zone of lower pressure, at a rate greater than that at which substantial foaming in the die orifice occurs and less than that at which substantial irregularities in cross-sectional area or shape occurs; and 5) permitting the ejected gel to expand unrestrained in at least one dimension to produce the foam structure.
The present foam structure may also be formed into non-crosslinked foam beads suitable for molding into articles. To make the foam beads, discrete resin particles such as granulated resin pellets are: suspended in a liquid medium in which they are substantially insoluble such as water; impregnated with a blowing agent by introducing the blowing agent into the liquid medium at an elevated pressure and temperature in an autoclave or other pressure vessel; and rapidly discharged into the atmosphere or a region of reduced pressure to expand to form the foam beads. This process is well taught in U.S. Pat. Nos. 4,379,859 and 4,464,484.
In a derivative of the above process, styrene monomer may be impregnated into the suspended pellets prior to impregnation with blowing agent to form a graft interpolymer with the ethylenic polymer material. The polyethylene/polystyrene interpolymer beads are cooled and discharged from the vessel substantially unexpanded. The beads are then expanded and molded by the conventional expanded polystyrene bead molding process. The process of making the polyethylene/polystyrene interpolymer beads is described in U.S. Pat. No. 4,168,353.
The foam beads may then be molded by any means known in the art, such as charging the foam beads to the mold, compressing the mold to compress the beads, and heating the beads such as with steam to effect coalescing and welding of the beads to form the article. Optionally, the beads may be impregnated with air or other blowing agent at an elevated pressure and temperature prior to charging to the mold. Further, the beads may be heated prior to charging. The foam beads may then be molded to blocks or shaped articles by a suitable molding method known in the art. (Some of the methods are taught in U.S. Pat. Nos. 3,504,068 and 3,953,558.) Excellent teachings of the above processes and molding methods are seen in C. P. Park, supra, p. 191, pp. 197-198, and pp. 227-229.
Blowing agents useful in making the present foam structure include inorganic agents, organic blowing agents and chemical blowing agents. Suitable inorganic blowing agents include carbon dioxide, nitrogen, argon, water, air, nitrogen, and helium. Organic blowing agents include aliphatic hydrocarbons having 1-6 carbon atoms, aliphatic alcohols having 1-3 carbon atoms, and fully and partially halogenated aliphatic hydrocarbons having 1-4 carbon atoms. Aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, or neopentane. Aliphatic alcohols include methanol, ethanol, n-propanol, and isopropanol. Fully and partially halogenated aliphatic hydrocarbons include fluorocarbons, chlorocarbons, and chlorofluorocarbons. Examples of fluorocarbons include methyl fluoride, perfluoromethane, ethyl fluoride, 1,1-difluoroethane (HFC-152a), 1,1,1-trifluoroethane (HFC-143a), 1,1,1,2-tetrafluoro-ethane (HFC-134a), pentafluoroethane, difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane. Partially halogenated chlorocarbons and chlorofluorocarbons for use in this invention include methyl chloride, methylene chloride, ethyl chloride, 1,1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1 difluoroethane (HCFC-142b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) and 1-chloro-1,2,2,2-tetrafluoroethane(HCFC-124). Fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-113), 1,1,1-trifluoroethane,pentafluoroethane, dichlorotetrafluoroethane (CFC-114), chloroheptafluoropropane, and dichlorohexafluoropropane. Chemical blowing agents include azodicarbonamide, azodiisobutyro-nitrile, benezenesulfonhydrazide, 4,4-oxybenzene sulfonyl-semicarbazide, p-toluene sulfonyl semi-carbazide, barium azodicarboxylate, N,Nxe2x80x2-dimethyl-N,Nxe2x80x2-dinitrosoterephthalamide, and trihydrazino triazine. Preferred blowing agents include isobutane, HFC-152a, and mixtures of the foregoing.
The amount of blowing agents incorporated into the polymer melt material to make a foam-forming polymer gel is from 0.2 to 5.0, preferably from 0.5 to 3.0, and most preferably from 1.0 to 2.50 gram moles per kilogram of polymer.
Foams may be perforated to enhance or accelerate permeation of blowing agent from the foam and air into the foam. The foams may be perforated to form channels which extend entirely through the foam from one surface to another or partially through the foam. The channels may be spaced up to 2.5 centimeters apart and preferably up to 1.3 centimeters apart. The channels are present over substantially an entire surface of the foam and preferably are uniformly dispersed over the surface. The foams may employ a stability control agent of the type described above in combination with perforation to allow accelerated permeation or release of blowing agent while maintaining a dimensionally stable foam. Excellent teachings to perforation of foam are seen in U.S. Pat. Nos. 5,424,016 and 5,585,058.
Various additives may be incorporated in the present foam structure such as stability control agents, nucleating agents, inorganic fillers, pigments, antioxidants, acid scavengers, ultraviolet absorbers, flame retardants, processing aids, or extrusion aids.
A stability control agent may be added to the present foam to enhance dimensional stability. Preferred agents include amides and esters of C10-24 fatty acids. Such agents are seen in U.S. Pat Nos. 3,644,230 and 4,214,054. Most preferred agents include stearyl stearamide, glycerol monostearate, glycerol monobehenate, and sorbitol monostearate. Typically, such stability control agents are employed in an amount ranging from 0.1 to 10 parts per hundred parts of the polymer.
The present foam structure exhibits excellent dimensional stability. Preferred foams recover 80 or more percent of initial volume within a month with initial volume being measured within 30 seconds after foam expansion. Volume is measured by a suitable method such as cubic displacement of water.
In addition, a nucleating agent may be added in order to control the size of foam cells. Preferred nucleating agents include inorganic substances such as calcium carbonate, talc, clay, titanium oxide, silica, barium sulfate, diatomaceous earth, mixtures of citric acid and sodium bicarbonate. The amount of nucleating agent employed may range from 0.01 to 5 parts by weight per hundred parts by weight of a polymer resin.
The foam structure is substantially noncross-linked or uncross-linked. The alkenyl aromatic polymer material comprising the foam structure is substantially free of cross-linking. The foam structure contains no more than 5 percent gel per ASTM D-2765-84 Method A. A slight degree of cross-linking, which occurs naturally without the use of cross-linking agents or radiation, is permissible.
The foam structure has density of less than 250, more preferably less than 100 and most preferably from 10 to 70 kilograms per cubic meter. The foam has an average cell size of from 0.05 to 5.0, more preferably from 0.2 to 2.0, and most preferably 0.3 to 1.8 millimeters according to ASTM D3576.
The foam structure may take any physical configuration known in the art, such as extruded sheet, rod, plank, and profiles. The foam structure may also be formed by molding of expandable beads into any of the foregoing configurations or any other configuration.
The foam structure may be closed-celled or open-celled. A closed cell foam contains 80 percent or more closed cells or less than 20 percent open cells according to ASTM D2856-A.
Additives such as antioxidants (e.g., hindered phenols such as, for example, Irganox(copyright) 1010, a registered trademark of CIBA-GEIGY), phosphites (e.g., Irgafos(copyright) 168, a registered trademark of CIBA-GEIGY), U. V. stabilizers, cling additives (e.g., polyisobutylene), antiblock additives, colorants, pigments, fillers, can also be included in the interpolymers employed in the blends of and/or employed in the present invention, to the extent that they do not interfere with the enhanced properties discovered by Applicants.
The additives are employed in functionally equivalent amounts known to those skilled in the art. For example, the amount of antioxidant employed is that amount which prevents the polymer or polymer blend from undergoing oxidation at the temperatures and environment employed during storage and ultimate use of the polymers. Such amount of antioxidants is usually in the range of from 0.01 to 10, preferably from 0.05 to 5, more preferably from 0.1 to 2 percent by weight based upon the weight of the polymer or polymer blend. Similarly, the amounts of any of the other enumerated additives are the functionally equivalent amounts such as the amount to render the polymer or polymer blend antiblocking, to produce the desired amount of filler loading to produce the desired result, to provide the desired color from the colorant or pigment. Such additives can suitably be employed in the range of from 0.05 to 50, preferably from 0.1 to 35, more preferably from 0.2 to 20 percent by weight based upon the weight of the polymer or polymer blend. However, in the instance of fillers, they could be employed in amounts up to 90 percent by weight based on the weight of the polymer or polymer blend.
The blends of the present invention, in addition to the production of foams, can be utilized to produce a wide range of fabricated articles such as, for example, calendered, cast and blown sheets and films and injection molded parts. The blends further find utilization in applications such as modifiers for bitumen and asphalt compositions and as components for hot melt and pressure sensitive adhesive systems.